The U.S. Secret Service yesterday defended its agents' response to an Iraqi journalist who threw a pair of shoes at President Bush during a Baghdad news conference, saying that they acted with the proper balance of aggressiveness and restraint.

Eric Zahren, a Secret Service spokesman in Washington, also said it will be up to Iraqi officials to prosecute Muntadar al-Zaidi, the journalist arrested in Sunday's incident.

"No one should read anything more into it than what it was, which was an individual throwing a shoe," Zahren said.

Zaidi, a reporter with the Cairo-based al-Baghdadia television network, stood up in the middle of the news conference and threw two shoes, one after the other, at Bush's head. The president, standing alongside Iraqi Prime Minister Nouri al-Maliki, dodged both shoes before Zaidi was tackled and restrained by U.S. and Iraqi security agents.

The incident quickly became a television and Internet sensation, and it prompted large rallies yesterday in Iraq and elsewhere in the Arab world by demonstrators demanding Zaidi's release. Throwing shoes is considered a dramatic insult among Arabs; Zaidi also called Bush a "dog."

The episode underscored the limits of the large security apparatus that surrounds U.S. presidents, a detail that must balance safety concerns against the need to be accessible, according to security experts.

"They are already so protected as it is that it's hard to imagine how they could guard against something like this," said John E. Pike, director of GlobalSecurity.org, a think tank on defense and security issues. "It just comes with the territory."

Zahren said that those at the news conference at the prime minister's palace were screened with magnetometers and were given additional pat-downs to ensure that no weapons were brought into the room. U.S. officials also conducted background and identity checks on all participants ahead of time as usual, he said.

"This was a room full of cleared and screened press, and that could be the case anywhere," Zahren said. "We wouldn't expect this type of behavior out of our press corps, but within the security structure, people can still misbehave."

William H. Pickle, a former Secret Service agent and former sergeant at arms in the Senate, said, "Other than the shoes, the most deadly weapon in that room was probably going to be a chair or a pen." He said there are limits to what security officers can do in such situations.

"Unless you isolate the president from human contact, I'm not sure you can entirely prevent someone from doing something like that," Pickle said.

Bush has been particularly well protected during his eight years in office, often limiting himself to pre-screened and friendly audiences. His weekend trip to Iraq and Afghanistan was unannounced and cloaked in secrecy.

One of the most serious security threats to Bush came in Tbilisi, Georgia, in 2005, when a live grenade was lobbed toward him as he addressed a crowd in Freedom Square. The grenade did not go off. The assailant later killed a security officer during a manhunt and was eventually sentenced to life in prison by Georgian authorities.